1. Field of the Invention
The present invention relates in general to a radiation image readout apparatus, and more particularly to a radiation image readout apparatus equipped with a readout portion, as well as an erasing portion for erasing the radiation energy remaining on a stimulable phosphor sheet after readout has been performed.
2. Description of the Related Art
In the field of radiology, there are in wide use today radiation image readout systems dependent upon radiation image readout apparatuses employing stimulable phosphor sheets, which contain stimulable phosphors that store a portion of radiation energy upon exposure thereto and emit stimulated emissions of a quantity corresponding to the radiation energy stored thereon upon exposure to visible or other stimulating light, to once record the image data of a radiation image obtained by storing a portion of the radiation passing through a subject, such as a human body, etc. on a stimulable phosphor sheet, wherein the stimulable phosphor sheet on which the radiation image has been recorded is scanned by a stimulating light such as a laser, and an image signal is obtained by photoelectrically reading out the stimulated emissions thereof.
According to the radiation image readout systems described above, after readout of the radiation image data, there remains on the stimulable phosphor sheet a quantity of radiation energy that was not completely dissipated during image readout. This energy (remaining radiation energy) originates in the radiation image data that had been stored on the stimulable phosphor sheet, and if it is of a level that cannot be ignored, the next time a radiation image is recorded on the stimulable phosphor sheet, the remaining radiation energy and the previous image are reproduced as noise. Because of this, it is necessary to erase this remaining radiation energy after image readout is performed.
To erase the remaining radiation energy, it can be caused to be emitted and dissipated; for example, a method can be used by which the stimulable phosphor sheet is exposed to ordinary light for a long period of time to dissipate the remaining radiation, or exposed to a high-intensity visible light for a short duration to accomplish the same. If erasable energy is applied to the stimulable phosphor sheet in this way, it is possible to reuse the stimulable phosphor sheet.
Generally, the radiation image readout apparatus employed in the radiation image readout system described above, aside from the readout portion, is also provided with an erasing portion for applying erasing energy to the sheet after readout of the image stored thereon is performed. The readout apparatus is configured so that the stimulable phosphor sheet is set therein and sent to the readout portion, wherein the image data as readout, and is then sent to the erasing portion, wherein the remaining radiation energy is dissipated, and after these continuous operations are complete, the sheet is discharged from the apparatus.
In this way, according to a general radiation image readout apparatus equipped with a readout portion and an erasing portion, after the image is readout from the stimulable phosphor sheet by the readout portion it is always sent to the erasing portion and subjected to erasing; however, because the erasing operation is performed by, for example, continuously exposing the sheet to erasing light for a only a certain period of time, the total time required for performing readout of the image (readout time) and the time required for erasing the remaining radiation energy (erasing time) is the operation time per sheet.
However, when used in conjunction with a group diagnosis, etc., in which radiation images for a large number of patients are readout, when it is necessary to perform readout of the images, from the stimulable phosphor sheets on which photographing has been completed, in a short time, because aforementioned readout and erasing operations are carried out in a continuous manner, a problem arises in that the operation time is excessively long.
On the other hand, there are radiation image readout apparatuses comprising only a readout portion, that is, that are provided with no erasing portion whatsoever. When such apparatuses are used, a method which is the opposite of the operation of the apparatus described above, that is, even for cases in which there is no shortage of time, because only readout is performed, without performing erasing, a sheet from which an image has been read out must be erased by a use of a specialized erasing apparatus, and handling of such an operation is cumbersome.
The present invention has been developed in consideration of the circumstances described above, and it is a primary objective of the present invention to provide a radiation readout apparatus for performing readout of a radiation image and erasing of remaining radiation in a manner corresponding to the needs of an operators circumstances: when there is a shortage of time, and when there is no shortage of time.
According to the first radiation readout apparatus according to the present invention, by making it possible to select whether or not erasing is to be performed after readout of a radiation image has been completed, readout and erasing operations can be performed in a continuous manner when there are no constraints on the overall operation time, and for cases in which there are constraints on the overall operation time, only the readout operation is given priority and the erasing operation is performed at another time so that the operation time can be shortened, and the apparatus is thereby capable of being employed in a manner suiting the needs of an operator.
That is to say, the first radiation apparatus according to the present invention comprises a readout portion for reading out the radiation image data cumulatively recorded thereon, and an erasing portion for erasing the remaining radiation energy remaining on the sheet after readout of the radiation image has been performed, and is also provided with a mode input means capable of selecting and inputting either the readout-and-erase mode, in which the remaining radiation erasing operation is performed after readout of the radiation image data, or the readout only mode, in which aforementioned erasing operation is not performed immediately after readout of the image data, and a mode control means for controlling at least the erasing portion with regard to whether the erasing operation is to be performed or not.
More specifically, the readout portion scans the stimulable phosphor sheet with a stimulating light, and photoelectrically reads out the quantity of stimulated emission emitted, corresponding to the radiation image data that has been cumulatively recorded on the stimulable phosphor sheet, and the erasing portion causes the radiation energy remaining on the sheet to be dissipated by apply erasing energy thereto. Note that the operation of applying erasing energy may consist of, for example, illuminating the stimulable phosphor sheet with a visible spectrum, etc. erasing light for a predetermined period of time.
In addition, with respect to the readout mode, the expression xe2x80x9cerasing operation is not performedxe2x80x9d refers not only to carrying out no erasing whatsoever, that is, where no erasing light is emitted, etc. and no erasing energy whatsoever is applied to the sheet, but includes, for example, cases in which, even though no erasing whatsoever is performed, the sheet must be conveyed through the erasing portion, and during only the minimal duration of the interval when the sheet is merely being conveyed through the erasing portion, the sheet is illuminated by erasing light and erasing, though insufficient erasing, is performed. That is to say, for cases in which the remaining radiation energy is erased from a stimulable phosphor sheet by the illumination thereof by erasing light, the erasing energy is prescribed by the product of the intensity and the duration of illumination, and in order to apply sufficient erasing energy to completely erase the radiation energy remaining on the stimulable phosphor sheet, it is necessary to convey the sheet through the erasing portion at a speed slower than that required for cases in which the sheet is simply passed through the erasing portion, so as to ensure for adequate illumination time for illumination of the sheet by the erasing energy; in this case, the throughput of the overall operation for the erasing operation is lowered. However, for cases in which the stimulable phosphor sheet is simply passed through the erasing portion, the throughput is not lowered, and although the incidental erasing light to which the sheet is exposed to during the interval in which it is passed through the erasing portion is not sufficient to completely erase the remaining radiation energy, erasing, though insufficient can be performed and the remaining radiation energy can be to a certain degree reduced, and there is a merit in that when the remaining radiation energy is erased afterwards by a separate operation, the time required therefor is shortened.
Regarding the erasing energy to be applied in the erasing operation of the erasing portion (meaning the operation performed in order to completely erase the remaining radiation energy), the level thereof required for erasing the remaining radiation energy can be calculated by obtaining, based on the electric signal obtained at the readout portion by photoelectrically reading out the stimulated emission emitted from the stimulable phosphor sheet, the quantity of remaining radiation, or alternatively, a separate erasing energy level detection means maybe provided for obtaining the level of erasing energy required for erasing the remaining radiation. Note that the level of erasing energy required can be selected corresponding to the level of the remaining radiation obtained, which is delineated in reference to, for example, 10 steps of levels which have been set in advance.
Input of the mode into the mode input means is performed by the operator of the radiation image readout apparatus.
The referent of the expression xe2x80x9cdo not perform the erasing operationxe2x80x9d with regard to the mode control means includes, as described above, performing no erasing whatsoever, as well as performing insufficient erasing, wherein the range of throughput has not been lowered. In addition, the selection control by the mode control means, corresponding to the mode, more specifically, entails the implementation of controls causing the erasing operation to be performed by the erasing portion in a continuous manner after readout has been performed by the readout portion, in the readout-and-erase mode, and in the read-only mode, entails the implementation of controls causing the readout operation to be performed and the erasing operation not to be performed after the readout operation has been performed.
For cases in which the radiation image readout apparatus is an apparatus wherein until the completion of the performance of the readout operation by the readout portion and the subsequent erasing operation by the erasing portion on a stimulable phosphor sheet, which are performed in a continuous manner, operations on the next stimulable phosphor sheet are not commenced (the so-called single plate  less than sheet greater than  reader), implementation of the present invention is particularly effective and advantageous. With this type of readout apparatus, although it is necessary that the stimulable phosphor sheet pass through the erasing portion, by selecting the readout-only mode, the sheet can be made to simply pass therethrough without performance of the erasing operation, and the effect whereby the operation time is shortened is great. Note that the expression xe2x80x9ccompletion of the performance of the readout operation by the readout portion and the subsequent erasing operation by the erasing portion, which are performed in a continuous mannerxe2x80x9d refers to the passing through of the sheet through the readout portion, after which, by being passed through the erasing portion, the operation on one sheet is complete.
Note that it is favorable that it is possible to select and input at the mode selecting means the readout-and-erase mode or the readout-only mode for the operation to be performed on each stimulable phosphor sheet. This is because the operation to be performed on each sheet can be conveniently made to meet the needs of each different operator. In this case, it is also favorable that the mode control means performs selection control with respect to the operation(s) to be performed on each sheet, corresponding to the mode that has been input at the mode input means.
It is preferable that in addition to the readout-and-erase and the readout-only modes, the mode input means is capable of selecting an erase-only mode wherein the readout operation is not performed by the readout means and only the erasing operation is performed by the erasing portion, whereupon the operation is complete, and that the mode control means, corresponding to the mode input to the mode input means, also controls the selection of whether or not the readout portion is to perform the readout operation or not. For un-erased sheets, which have hitherto been subjected to processing wherein the readout-only mode was selected and the erasing operation was not performed, there is no need to perform readout, and because it is only necessary to perform the erasing operation thereon, by being configured in this way, the time required to pass through the readout portion can be shortened, with respect to un-erased sheets, and only the erasing operation (complete erasing of the remaining radiation) can be performed.
In this case, it is more favorable that a sheet-specific information input means, into which specific information for each sheet that is to be the subject of operations is input, as well as a recording means for recording, at least in the readout-only mode, on a predetermined storage medium the erasing energy level, correlated to the sheet-specific information entered into the sheet-specific information input means for each stimulable phosphor sheet that is to become the subject of a readout operation, required to erase the remaining radiation on said stimulable phosphor sheet, wherein the erasing portion, in the erase-only mode, based on the erasing energy level correlated to the sheet-specific information recorded on the predetermined storage medium for each stimulable phosphor sheet to become the subject of an erasing operation, performs the erasing operation thereon.
The second radiation readout apparatus according to the present invention performs the erasing operation after readout of the radiation image, in a non-continuous manner at a later time, and by making it possible to selectively perform only the erasing operation on sheets that have not been erased, the time required to perform the unnecessary readout operation omitted and the operation time shortened.
That is to say, the second radiation readout apparatus according to the present invention comprises a readout portion for reading out the radiation image data cumulatively recorded on a stimulable phosphor sheet, and an erasing portion for erasing the radiation energy remaining on a stimulable phosphor sheet after readout of the radiation image data contained thereon has been performed, and further comprises a mode input means for inputting a selectable erase-only mode in which the readout operation is not performed by the readout portion and only the erasing operation is performed by the erasing portion, whereupon the operation is complete, a mode control means for controlling selection of whether or not the readout portion and erasing portion are to perform or not perform each of the operations, and an erasing energy level detection means for detecting, at least in the erase-only mode, the erasing energy level required for erasing the radiation energy remaining on a stimulable phosphor sheet that is the object of an erasing operation, wherein said erasing portion performs aforementioned erasing operation, based on the erasing energy level detected by the erasing energy level detecting means.
Here, the selection control by the mode control means, corresponding to the mode, more specifically, for the erase-only mode, entails implementing controls so that the readout portion does not perform the readout operation and the erasing portion performs the erasing operation, and for modes other than the erase-only mode, entails implementing controls so that at least the readout operation is performed by the readout portion. Modes other than the erase-only mode can include: as in the operation of the radiation image readout apparatus described above, the readout-and-erase mode, which is controlled so that performance of the erasing operation by the erasing portion is performed in a continuous manner after readout of the radiation image data by the readout portion; the readout-only mode, which is controlled so that the readout portion performs the readout operation, but the erasing portion does not perform the erasing operation; or both of these modes, etc.
The erasing energy level detection means, more specifically, for example, performs an operation such as detecting the quantity of radiation energy remaining on a stimulable phosphor sheet by illuminating the sheet with a stimulating or visible spectrum of light, photoelectrically reading out the quantity of light emitted as a stimulated emission, corresponding to the quantity of radiation energy remaining on the sheet, and obtaining an electric signal thereof, and based on this electric signal, computes the level of erasing energy required to erase the radiation energy remaining on the sheet. Note that according to the second radiation image readout apparatus of the present invention, because it is possible to select the erase-only mode, in which the readout portion does not perform the readout operation, as in the first radiation image readout apparatus, a function of detecting the remaining radiation energy cannot be combined with the structures of the readout portion used for performing readout of a radiation image, and therefore, even when the readout portion does not perform the readout operation, detection of the remaining radiation energy can be performed independently and an independent erasing energy level detection means must be provided.
According to the first radiation image readout means of the present invention, the erasing operation is performed following the readout operation, and by making it possible to select whether it is performed or not, when there is no shortage of overall operation time, the readout and erasing operations are performed in a continuous manner as a consecutive series, and when there is not sufficient overall operation time, the erasing operation only is performed at a later time, and the readout time can be shortened or the conditions of an operator can be accommodated.
That is to say, after the sheet has been set in the readout apparatus it is passed through the readout portion, and in a readout apparatus in which passing the sheet through the erasing portion afterwards is unavoidable, when it is necessary to perform readout on a large number of sheets in a short time, by selecting the read-only mode, performance of the erasing operation on a large number of sheets is omitted and only the readout operation is performed on said sheets, whereby the operation time can be shortened by the amount of time that would have been required to perform the erasing operation on the sheets. Note that as for un-erased sheets, the erasing operation can be performed for the group of sheets at a later date when there is ample time therefor.
The radiation image readout apparatus according to the present invention is particularly effective when implemented in a single-sheet reader, in which a single sheet is set in the readout apparatus and passed through the readout portion, after which it is also passed through the erasing portion and then discharged from the readout apparatus, and the next sheet is loaded, in that an effect whereby a substantial shortening of operation time can be obtained.
According to the second radiation image readout apparatus of the present invention, the erasing operation, which was performed in a continuous manner following the readout operation in the first radiation image readout apparatus described above, is performed at a later time and in a non-continuous manner with the readout operation, and by making it possible that only the erasing operation be selectively performed on sheets that have not been erased, the time required to perform the readout operation, which is unnecessary for sheets that have already been readout is omitted and operation time shortened. That is to say, according to readout apparatuses whose operation is such that a sheet is set in the apparatus and passed through the readout portion and then must also be passed through the erasing portion, for cases in which only the erasing operation is to be performed, by selecting the erase-only mode, the readout operation, which consumes a comparatively large amount of time and electricity, is omitted and only the erasing operation is performed